This invention relates generally to a pneumatic tire pressure regulation system to inflate and deflate the tire as needed in order to maintain the air pressure in the tire at an optimum value and more specifically to an automatic tire pressure regulation system which requires no compressor or outside source of pressurized air.
Maintaining optimum tire pressure in a vehicle is important for safety and fuel efficiency. The Transportation Recall Enhancement, Accountability and Documentation (TREAD) Act is a United States federal law enacted in 2000. One of the mandates of the TREAD Act is to implement a suitable Tire Pressure Monitoring System (TPMS) technology in all light weight motor vehicles to alert drivers of under-inflated tires. Currently all tires implement TPMS. TPMS alerts a driver only when the pressure is below a certain minimum threshold value that renders the tire to be unsafe. While the TPMS can send the actual tire pressure value to the vehicle computer for display to the driver, it is not practical that the driver would inflate the tire whenever the pressure is below the optimum value but still above the safety threshold value. Both safety and fuel efficiency are compromised when the pressure is below the optimum value even if not as low as the threshold value.
Tire pressure changes significantly with the outside ambient temperature. As a result, it is desirable to adjust tire pressure seasonally for fuel efficiency and to some extent better safety even if the pressure is above the TPMS threshold value but below the optimum value. Frequent tire inflation checking and pressure adjustment is a chore that drivers would not perform. It would be desirable if the task of checking as well as properly inflating tires is completely eliminated. Thus there is a need for an automatic tire pressure system that inflates and deflates the tire as needed to maintain the recommended optimum tire pressure all the time without the driver's intervention.
Attempts have been made previously to provide automatic tire pressure inflating systems. Examples of such attempts are found in the U.S. Pat. Nos. 939,020; 1,029,340; 1,327,371; 1,456,567; 2,021,646; 2,420,224; 4,269,252; 4,651,792; and U.S. Pat. Nos. 6,401,743; and 8,113,234. Most of these systems require a pump housed inside the tire or the tube of the tire and is operated by the compression or flexing of the tire. One drawback of these systems is that frequent direct impact of the pump levers on the tire itself tends to damage the tire and the pumping mechanism. Second drawback is that the manufacturing and installation of such systems inside the tire is complex and expensive. Other systems require an external source of compressed air. This type of devices has already been available and used mostly in heavy trucks and recreational vehicles. The main drawback of such devices for application in light weight vehicles is the complexity and high cost.
Thus there is a need for an automatic tire pressure system that does not require an external source of compressed air and that is simple, inexpensive, easier to manufacture, and durable.